Claim: the greenhouse effect being logarithmic means global warming ain't a problem

A common claim you see among the Global Warming contrarians is the postulation that since the greenhouse effect is logarithmic, as in it has a diminishing effect in proportion to an equal rise in CO2, it therefore must implicitly follow that any global warming experienced will not be significant, or that it won't get severe enough to have a significant adverse effect. To quote fossil fuel stan Alex Epstein again:
While I’ve met thousands of students who think the greenhouse effect of CO2 is a mortal threat, I can’t think of ten who could tell me what kind of effect it is. Even “experts” often don’t know, particularly those of us who focus on the human-impact side of things. One internationally renowned scholar I spoke to recently was telling me about how disastrous the greenhouse effect was , and I asked her what kind of function it was. She didn’t know. What I told her didn’t give her pause, but I think it should have.

As the following illustration shows, the greenhouse effect of CO2 is an extreme diminishing effect–a logarithmically decreasing effect. This is how the function looks when measured in a laboratory.
This is the graph Epstein cites:
1644855897691.png

The first major issue is that Epstein fails to elaborate on the expertise of the scholar he mentioned. Is she a climatologist or meteorologist? Does she have any relevant expertise in climate issues? Even if she does, it is a fallacy of hasty generalisation to assume that the relevant experts often don't know just because one scholar of unverified expertise doesn't know. This is a rhetorical sleight of hand meant to cast doubt on the relevant climate experts by making it seem like they don't even know the basic fact that CO2 is logarithmic, which makes them intellectually inferior to Epstein and his grand wisdom.

Assuming that it is valid for the sake of argument, it still does not prove his thesis at all in any way. This is because the bulk of the logarithmic effect occurs within CO2 concentrations at preindustrial levels and below. As CO2 rises above preindustrial levels, the logarithmic effect vastly diminishes. In effect, any logarithmic effect after rises in CO2 concentration above preindustrial levels is so small as to be insignificant, rendering any warming experienced roughly linear.

But all that aside, just because greenhouse forcing is logarithmic does not mean that whatever forcing there is won't have a significant if not adverse effect on the climate. It could be the case that forcing above preindustrial levels will decrease with each unit increase, as in it could be the case that an increase in CO2 from 280 to 560ppm will increase temperatures by 5 degrees, and an increase from 560 to 940ppm would increase temperatures by 3 degrees. Though the greenhouse effect is logarithmic in this case, it still results in a significant increase in global temperature by 8 degrees. This also isn't even factoring into the fact that CO2 has increased exponentially; so exponentially that even when graphed on a logarithmic scale, the increase in CO2 is still an upwards curve when it should, like all other exponential lines, be flat according to SkepticalScience:
Screen Shot 2022-02-17 at 2.19.47 am.png
So even if Epstein was right about the logarithmic greenhouse effect, this still does not imply that future warming won't be severe enough to have adverse effects on human civilisation. Double the current CO2 levels any number of times, and you will begin to see a significant warming trend.

So that's my take for today, and as Epstein would make a few more points in the article I linked, I will be following up with another post in this thread soon. Did I miss out on any important details? Let me know.
 

qed

Senior Member
You are correct.

We must take the Figure 4 logarithmic graph of CO2 emission by time, which show that C02 emissions are currently growing exponentially with time, and input this data into the first graph of effect with respect to CO2 (Epstein). The exponential growth in CO2 inverts the logarithmic effect, and we end up with the graph of effect w.r.t time being a diagonal line directed upwards.

The effect is only going to get worse with time, and will not flatten out, unless we reduce reduce carbon emissions to flatten or reduce this curve.

The situation is in fact worse. Figure 4 shows increasing exponential growth: it is not a straight diagonal line, it's logarithm would not be a flat line.
 
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Henk001

Senior Member.
A common claim you see among the Global Warming contrarians is the postulation that since the greenhouse effect is logarithmic, as in it has a diminishing effect in proportion to an equal rise in CO2, it therefore must implicitly follow that any global warming experienced will not be significant, or that it won't get severe enough to have a significant adverse effect. To quote fossil fuel stan Alex Epstein again:

This is the graph Epstein cites:
1644855897691.png

The first major issue is that Epstein fails to elaborate on the expertise of the scholar he mentioned. Is she a climatologist or meteorologist? Does she have any relevant expertise in climate issues? Even if she does, it is a fallacy of hasty generalisation to assume that the relevant experts often don't know just because one scholar of unverified expertise doesn't know. This is a rhetorical sleight of hand meant to cast doubt on the relevant climate experts by making it seem like they don't even know the basic fact that CO2 is logarithmic, which makes them intellectually inferior to Epstein and his grand wisdom.

Assuming that it is valid for the sake of argument, it still does not prove his thesis at all in any way. This is because the bulk of the logarithmic effect occurs within CO2 concentrations at preindustrial levels and below. As CO2 rises above preindustrial levels, the logarithmic effect vastly diminishes. In effect, any logarithmic effect after rises in CO2 concentration above preindustrial levels is so small as to be insignificant, rendering any warming experienced roughly linear.

But all that aside, just because greenhouse forcing is logarithmic does not mean that whatever forcing there is won't have a significant if not adverse effect on the climate. It could be the case that forcing above preindustrial levels will decrease with each unit increase, as in it could be the case that an increase in CO2 from 280 to 560ppm will increase temperatures by 5 degrees, and an increase from 560 to 940ppm would increase temperatures by 3 degrees. Though the greenhouse effect is logarithmic in this case, it still results in a significant increase in global temperature by 8 degrees. This also isn't even factoring into the fact that CO2 has increased exponentially; so exponentially that even when graphed on a logarithmic scale, the increase in CO2 is still an upwards curve when it should, like all other exponential lines, be flat according to SkepticalScience:
Screen Shot 2022-02-17 at 2.19.47 am.png
So even if Epstein was right about the logarithmic greenhouse effect, this still does not imply that future warming won't be severe enough to have adverse effects on human civilisation. Double the current CO2 levels any number of times, and you will begin to see a significant warming trend.

So that's my take for today, and as Epstein would make a few more points in the article I linked, I will be following up with another post in this thread soon. Did I miss out on any important details? Let me know.
There is no doubt about the logarithmic relation between radiative forcing and CO2 concentration. But Epsteins reasoning is a non sequitur. It is a bit like what you could hear from the merchants of doubt a few decades ago, that 400 ppm CO2 is such a tiny amount, that it could not possibly have any effect on temperature.
It doesn't matter how mathematically CO2 causes whatever temperature rise -- logarithmically, quadratically, or ? -- the question should be, what effects does a certain temperature rise have on our lives?
The "scholar" (vague...) could have any expertise in a wide range of specialisms that are all too easily lumped together onder the name "climate science". It could be astronomy, atmospheric physics, glaciology, geology, ecology, paleontology, chemistry, etc. A glaciologist could tell us more about the effects of temperature rise on sea level rise than an atmospheric physicist, whereas the latter knows more about how CO2 absorbs longwave radiation.
 

Ann K

Active Member
A misunderstanding arises when the concentration of CO2 is measured at the surface of the earth, when it is the layer miles up in the troposphere that forms the "greenhouse" layer. The gases at that altitude cannot readily mix nor react with the surface without a lag time of decades-to-centuries. Bottom line: there is no quick fix, and whatever we've produced in CO2 in recent days will be around to affect the climate our grandchildren will have. And contrary to the claims of the rabid anti-warming crowd, "The trees will take up CO2" is wishful thinking.
 
Moving on...

Epstein proceeds to claim that climate models haven't matched temperature observations as follows:
Here’s the summary of what has actually happened– a summary that nearly every climate scientist would have to agree with. Since the industrial revolution, we’ve increased CO2 in the atmosphere from .03 percent to .04 percent, and temperatures have gone up less than a degree Celsius, a rate of increase that has occurred at many points in history. Few deny that during the last fifteen-plus years, the time of record and accelerating emissions, there has been little to no warming– and the models failed to predict that. By contrast, if one assumed that CO2 in the atmosphere had no major positive feedbacks, and just warmed the atmosphere in accordance with the greenhouse effect, this mild warming is pretty much what one would get.

Thus every prediction of drastic future consequences is based on speculative models that have failed to predict the climate trend so far and that speculate a radically different trend than what has actually happened in the last thirty to eighty years of emitting substantial amounts of CO2.
The first issue with Epstein's claim is that he mentions the increase in CO2 in terms of a percentage of atmospheric composition rather than in terms of parts per million. This allows him to make the CO2 increase seem insignificant, which essentially implicitly reiterates the common contrarian canard that ''CO2 is a tiny amount of the atmosphere, ergo it must not have a significant effect.'' Though Epstein might accuse me of strawmanning him (if he even knows I exist), it isn't a strawman because that's exactly the conclusion many people will draw when he mentions the rise in CO2 as a percentage of atmospheric composition.

The second fallacy Epstein makes is mentioning that the same rate of increase we're currently observing has occurred in the past. Even assuming what he says is true, it does not follow that either the current period of warming isn't going to accelerate in the future with increasing CO2, nor does it follow that it won't have or isn't already causing adverse effects on the climate.

The third fallacy that Epstein makes is mentioning that the warming has been relatively stagnant in the past 15 years preceding. Even if this is true, expecting the trends in CO2 emissions to exactly and perfectly sync up with the trends in temperature is fantastical, and cherry picking tiny periods where warming has been stagnant while CO2 has been rising is another tired old contrarian canard.

Epstein then reinforces his claims by citing this graph developed by known contrarian climate/atmospheric scientist John Christy:
1645064550465.png
Seems pretty damning for the theory of global warming, right? Not so fast. Gavin Schmidt, climatologist and director of the NASA Goddard Institute for Space Studies, proceeds to explain what is wrong with Christy's graph in this RealClimate article.

Now I don't currently have the time nor the understanding on climate science to go through the article, so I'mma leave the analysis of it along with Christy's data to you guys for now.
 

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Mendel

Senior Member.
Gavin Schmidt, climatologist and director of the NASA Goddard Institute for Space Studies, proceeds to explain what is wrong with Christy's graph in this RealClimate article.
In the end, Schmidt produces his own graphs:
christy_new.png
christy_trend.png
Content from External Source
These graphs show that there is uncertainty in the satellite data, but there's still a discrepancy between model projections and observations.

A commenter notes that a climate model makes assumptions about future events such as volcano eruptions etc., and so what we should do to assess the validity of the model is to pick the projection where the assumptions match reality, instead of comparing to the ensemble or the average.

Another point is that 15 years is "weather" and not climate, and that it's become warmer again after 2015.

From your Epstein quote:
temperatures have gone up less than a degree Celsius, a rate of increase that has occurred at many points in history.
Content from External Source
I think the point to be made here is that if these historic increases are consistent with and explained by our current climate science, then we should trust that science when it says that this time, it's different.
 
A commenter notes that a climate model makes assumptions about future events such as volcano eruptions etc., and so what we should do to assess the validity of the model is to pick the projection where the assumptions match reality, instead of comparing to the ensemble or the average.
So you're saying that the best way to assess the accuracy of a model is to select the models, or the projections thereof, that are the closest match to the observed temperature trends, as opposed to comparing the ensemble or average of the climate models to the real temperatures?
 

Amber Robot

Active Member
The first major issue is that Epstein fails to elaborate on the expertise of the scholar he mentioned. Is she a climatologist or meteorologist? Does she have any relevant expertise in climate issues? Even if she does, it is a fallacy of hasty generalisation to assume that the relevant experts often don't know just because one scholar of unverified expertise doesn't know. This is a rhetorical sleight of hand meant to cast doubt on the relevant climate experts by making it seem like they don't even know the basic fact that CO2 is logarithmic, which makes them intellectually inferior to Epstein and his grand wisdom.
In fact, pointing out that the “scholar” was actually in a relevant field would only strengthen his argument so the fact he declines to state what kind of scholar the person was casts immediate doubt that they were relevant.

He seems to hope that the mere juxtaposition of the word “scholar” in that sentence with the reference to “experts” in the previous sentence will cause the casual reader to conflate the two.
 

Mendel

Senior Member.
So you're saying that the best way to assess the accuracy of a model is to select the models, or the projections thereof, that are the closest match to the observed temperature trends, as opposed to comparing the ensemble or average of the climate models to the real temperatures?
If I want to assess the quality of models that were used in 2000 to predict the next 15 years, I would choose those model runs where the input parameters matched what actually happened in 2000-2015.
 
Another point I would like to make about Epstein's claim that the warming currently experienced is somehow insignificant as it is less than a degree is that even a warming slightly less than a degree is already a significant portion, as in almost a fifth, of the warming that brought the Earth out of the last ice age. To quote the 2009 book ''Climate Change, the Science, Impacts and Solutions'' by Albert Barrie Pittock - a ''climate researcher'' (for the lack of a better term as I wasn't able to find good info on his precise expertise):
Three things are notable about these IPCC conclusions. First, it shows that a warming of at least 0.56ºC almost certainly occurred. Second, the most likely value of 0.74ºC, while it may appear to be small, is already a sizeable fraction of the global warming of about 5ºC that took place from the last glaciation [ice age] around 20,000 years ago to the present interglacial period (which commenced some 10,000 years ago). Prehistoric global warming led to a complete transformation of the Earth's surface, wth the disappearance of massive ice sheets, and continent wide changes in vegetation cover, regional extinctions and a sea level rise of about 120 metres.

- ''Climate Change, the Science, Impacts and Solutions'' p.3
In case anyone needed further data on the temperature trends of the past 20,000 years, here is a good graph from Wikipedia, with sources attached.
1645678087349.png
As you can see in the fifth segment, the temperature increase from the interglacial period does appear to match up with Pittock's statements. In addition, all the proxy data and temperature records were published before Epstein's article.

But all that aside, the rate of warming also matters just as much as the amount of warming. This to which Pittock has the following to say:
Most importantly, the average rate of warming at the end of the last glaciation was about 5ºC in some 10,000 years, or 0.05ºC per century, while the observed rate of warming in the last 50 years is 1.3ºC per century and the estimated rate could be more than 5ºC per century, which is 100 times as fast as during the last deglaciation. such rapid rates of warming would make adaptation by natural and human systems extremely difficult or impossible.
However, the rate of warming over such a period isn't consistent, and the Greenland Ice Core data in the above graph noted several periods of extremely rapid warming during the last deglaciation (periods termed Dansgaard-Oeschger events). So could Pittock be cherry picking when he compares the average warming rate of the past 50 years with a longer average warming rate of approx. 10,000 years? Especially since the warming rate during then isn't that consistent?
 

Mendel

Senior Member.
To quote the 2009 book ''Climate Change, the Science, Impacts and Solutions'' by Albert Barrie Pittock - a ''climate researcher'' (for the lack of a better term as I wasn't able to find good info on his precise expertise):
Article:
(Albert) Barrie Pittock worked at the Aspendale laboratory, CSIRO Marine And Atmospheric Research from 1965 until officially retiring on 1999. Since then he worked as a CSIRO honorary Fellow until 2017. Barrie did research in Meteorology, Geochemistry and Climatic change and impacts, and has continuinig interest in renewable energy and policy re climate change. He is still writing and archiving re his career and interests, and received an Order of Australia medal in 2019 for his voluntary work on Aboriginal affairs since the late 1950s, including renewable energy as a major resource for Aboriginal communities.

That page also lists a number of his publications. I think it's fair to call him a climate scientist without "apostrophes".
 

Ann K

Active Member
In case anyone needed further data on the temperature trends of the past 20,000 years, here is a good graph from Wikipedia, with sources attached.
1645678087349.png
Edit to add: cut-n-paste unfortunately truncated the salient portion of the graph. Darn it! Try again:
https://upload.wikimedia.org/wikipedia/commons/f/f5/All_palaeotemps.png

I find it illuminating - and chilling - that almost all of what we refer to as civilization occurs during that ten thousand years of relatively stable temperature. Perhaps it's because that's the period when most people no longer had to spend all their time on sheer survival.

Nice world. Be a shame to lose it...
 
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